[ndnSIM] question about faceIterator in CustomStrategy

yao hu huyao0107 at gmail.com
Sat Mar 30 21:34:19 PDT 2013

Hi Alex,

Thanks for your reply. That means SetDefaultRoutes(true) does not conflict
with my later implementation in ccnxHelper.SetForwardingStrategy
("ns3::ndn::fw::CustomStrategy")? That is, before installing stack on
nodes, the following codes is ok?

  ndn::StackHelper ccnxHelper;
  *ccnxHelper.SetForwardingStrategy ("ns3::ndn::fw::CustomStrategy");*
  *ccnxHelper.SetDefaultRoutes (true);*
  ccnxHelper.SetContentStore ("ns3::ndn::cs::Lru",
                              "MaxSize", "1"); // ! Attention ! If set to
0, then MaxSize is infinite
  ccnxHelper.InstallAll ();


2013/3/31 Alex Afanasyev <alexander.afanasyev at ucla.edu>

> Hi huyao,
> You still have to have an entry in FIB that corresponds to forwarded
> interests.  This entry is part of overall logic to forward interests, data,
> and record data performance stats for the forwarded data.
> In your case, you can have an entry that corresponds to "/" prefix.  The
> easiest way to do it, is to use ndn::StackHelper::SetDefaultRoutes(true),
> which will create this entry and fill with all available faces (which you
> can ignore later).
> ---
> Alex
> On Mar 30, 2013, at 8:33 PM, yao hu <huyao0107 at gmail.com> wrote:
> Hi Alex,
> I see. I forgot about it. Thanks for your explanation. I am sorry I have
> one question about flooding strategy in ndnsim.
> I saw your reply
> http://www.lists.cs.ucla.edu/pipermail/ndnsim/2012-December/000030.html that
> mentions how to flood to all available faces not listed in FIB. Now I
> assume that when ndnsim simulation starts, I do not manually configure FIB
> routes by AddRoute, that is, FIB on each node is empty, and let each node
> forward the incoming interest to all available faces and don't want them
> to add to FIB entries by the following
> Ptr<L3Protocol> ndn = this->GetObject<L3Protocol> (); for (uint32_t
> faceNum = 0; faceNum < ndn->GetNFaces (); faceNum++) { Ptr<Face> outFace =
> ndn->GetFace (faceNum); TrySendOutInterest (inFace, outFace, header,
> origPacket, pitEntry); }
> However the interest will be not forwarded from any face and it seems no
> interest packet is produced. What is wrong with it? Thanks a lot.
> Regards,
> huyao
> 2013/3/31 Alex Afanasyev <alexander.afanasyev at ucla.edu>
>> Hi huyao,
>> The data structure that stores ordered Face instances in FIB behaves like
>> any other STL container:
>> begin ()  returns iterator to first element in the container
>> end () returns a special iterator, indicating element just after the last
>> valid element
>> In other words, end () is never an iterator to a valid element in the
>> container, and situations when begin () == end () means that the container
>> has no elements.  If there is at least one element in the container, begin
>> () will return iterator to a valid first element.
>> ---
>> Alex
>> On Mar 30, 2013, at 8:20 AM, yao hu <huyao0107 at gmail.com> wrote:
>> Hi Alex,
>> Thanks for your reply to the previous question about ndnsim update.
>> Now I am looking into the CustomStrategy::DoPropagateInterest. This
>> function is to let Interest be forwarded to first two best-metric faces
>> specified by FIB. However, in the codes, the faceIterator is first pointed
>> to the beginning of faces ordered by metric and then checked whether it is
>> pointed to the end of the faces. Assume that there is only one face
>> existing in the associated faces for the fib entry. For my understanding,
>> this face is located at the beginning of the faces and also should be
>> located at the end of the faces. Then according to the DoPropagateInterest
>> algorithm, the incoming interest will be not sent out though the fact is
>> not like that for sure. So what is wrong with my understanding for the
>> faceIterator? Or what is the internal structure of FacesByMetric &faces
>> especially faces.begin () or faces.end()?
>> I am sorry for my confusing expression. Thank you very much!
>> Regards,
>> huyao
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